Antioxidant Activity Measurement

The antioxidant activity % of the CH film was measured using the DPPH and ABTS tests outlined by Liu et al. [60]. In brief, 1.5 mL of the film extract was combined with 0.5 mL of a 0.1 mM ethanolic DPPH solution and stored in the dark for half an hour. The DPPH scavenging capacity % was determined from Equation (8) based on the absorbance at 515 nm.

$$\text{DPPH saving} \left(\% \right) = \left[ 1 - \frac{\text{film extracted absorption}}{\text{control absorption}} \right] \times 100 \tag{8}$$

For the test of ABTS scavenging %, the film samples (10 mg) and 3 mL of ABTS stock solutions were combined, absorbance at 734 nm was measured, and scavenging activity was estimated using the following equation:

$$\text{ABTS saving} \left(\% \right) = \left[ 1 - \frac{\text{film extracted absorption}}{\text{control absorption}} \right] \times 100 \tag{9}$$
